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Studies on Fracton in Silica Aerogels by Ramman Scattering

二氧化硅气凝胶中分形子的拉曼散射研究

基本信息

批准号：
02640243
负责人：
TSUJIMI Yhuji
金额：
$ 0.96万
依托单位：
Hokkaido University of Education
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

In 1990 fiscal year, Ramman scattering and neutron inelastic scattering experiments were performed. The results are reported in Phys. Rev. Letters and is summarized as follows. Two samples were prepared in PH7 solvent(N-sample)and in PH8.5 solvent(B-sample). Compared Ramman scattering result with neutron scattering result, we found that there exist two types of fracton. One is scaler fracton observed above crossover frequency nu e=10GHz and the another is vector fraction observed below nu e. In N-sample, fracton dimension of scaler fracton d^^=_s and that of vector fraction d^^=_b are determined to be 1.3 and 2.2, respectively. In B-sample, d^^=_s=0.9 and d^^=_b=1.7. Here fracton dimension is a physical quantity characterizinle, dynamic behavior of fracton. Results show that fractal dimension depends on PH and is not the universal physical quantity. Relation d^^=_s<d^^=_b is, however, hold both in N- and B-sample.In 1991 fiscal year, four samples x-7ere prepared in PH 7.03 7.5, 8.0 and 8.5 solvents. The purpose is to obtain a detailed information about the dependence of fracton on PH. Thouch Ramman scattering experiment was made, the very strong elastic scattering prevented us to observe fracton. This comes from poor contrast of 5 path interferometer(Burleigh RC-110)used in Hokkaido University. Until we introduce the 3+3 path tandem interferometer(contrast is about 10^<15>)we put off Ramman scattering experiment. Brillouin scattering experiment in beta-BiNbO_4 was performed instead. The elastic constants were determined in cylindrical sample alona a^* axis of beta-BiNbO_4. This result was reported at annual meeting of Physical Society of Japan in 1992.

1990财年进行了拉曼散射和中子非弹性散射实验。研究结果发表在《物理学》杂志上。Rev. Letters并总结如下。两种样品分别在PH7溶剂（n -样品）和PH8.5溶剂（b -样品）下制备。将拉曼散射结果与中子散射结果进行比较，发现存在两种类型的分形。一个是在交叉频率nu e=10GHz以上观测到的标量分数，另一个是在nu e以下观测到的矢量分数。在n个样本中，确定标量分数d^^=_s的分数维为1.3，矢量分数d^^=_b的分数维为2.2。在b样本中，d^^=_s=0.9, d^^=_b=1.7。这里的分数维数是表征分数动态行为的物理量。结果表明，分形维数与PH值有关，并非通用物理量。然而，关系d^^=_s<d^^=_b在N-和b -样本中都成立。在1991财政年度，在PH 7.03、7.5、8.0和8.5溶剂中制备了四个样品x-7。为了详细了解分数对ph值的依赖关系。虽然进行了拉曼散射实验，但很强的弹性散射使我们无法观察分数。这是由于北海道大学使用的5路干涉仪（Burleigh RC-110）对比度差造成的。在引入3+3路串列干涉仪（对比度约为10^<15>）之前，我们推迟了拉曼散射实验。用β - binbo_4进行布里渊散射实验。沿β - binbo_4的a^*轴测定了柱状试样的弹性常数。这一结果在1992年日本物理学会年会上发表。